In a typical service station there are several underground or below ground storage tanks, each tank for a different type of fuel. Fuel is directed to each tank through an opening at ground level. The opening is enclosed by a removable access cover. Access covers can be colored to prevent cross-contamination of different types of fuel. For example, a yellow cover may correspond to diesel fuel and a red cover may correspond to high octane gasoline. The coloring of the access cover can be integral with the access cover or the access cover can be painted.